silverone wrote:Sorry about my first post being in a controversial subject! No disrespect was intended to any of the forum membership.

and none was taken. We only want to make sure you understand what is going on. That is all. Some will read your post and take it to mean the Chevy Volt battery is far superior to the LEAF which is simply not true. They have simply managed it much different because they have the luxury of gas.

GRA wrote:Just to be clear, the Volt's battery has suffered degradation but because GM decided to only use 65% of the total capacity when new, that degradation is hidden from the owner. In addition, they employed a very effective active TMS which slows down the rate of heat-related degradation, which combined with the relatively small SoC window allowed when new and the ability to open up that window as the battery ages, allows the Volt to appear to have no degradation from the user's perspective over a prolonged period of time.

Re: the bolded part, I've heard the Volt opening up more capacity as the battery degrades passed around both as speculation and fact by several different folks. I've also heard Volt folks claiming that the Volt does NOT do that.

I'm not clear who's right. Logically, it'd make sense for GM to do that. Whether or not they do it is a question...

If anyone has a definitive answer, preferably different independent sources providing evidence of one or the other, I'd like to know.

GRA wrote:Just to be clear, the Volt's battery has suffered degradation but because GM decided to only use 65% of the total capacity when new, that degradation is hidden from the owner. In addition, they employed a very effective active TMS which slows down the rate of heat-related degradation, which combined with the relatively small SoC window allowed when new and the ability to open up that window as the battery ages, allows the Volt to appear to have no degradation from the user's perspective over a prolonged period of time.

Re: the bolded part, I've heard the Volt opening up more capacity as the battery degrades passed around both as speculation and fact by several different folks. I've also heard Volt folks claiming that the Volt does NOT do that.

I'm not clear who's right. Logically, it'd make sense for GM to do that. Whether or not they do it is a question...

If anyone has a definitive answer, preferably different independent sources providing evidence of one or the other, I'd like to know.

Not definitive but I've seen posts from GM engineers insist that the capacity window does not open up or change. This was on FB Q&A posts at the Gen 2 release as well as the GM Volt forums. There are also no consumer tools to measure it, as the closest we have is SOC. On the Volt this is just a calculated number from other readings.

Supporting this, you would realistically not expect to see the whole 35% battery "buffer" be available to supplement any range loss experienced. The range loss of a smaller battery should be more noticeable than a larger battery as well. Compare a 50,000 EV mile Leaf with a 50,000 mile EV Volt and the Volt will have way more charge cycles in that timeframe - yet no degradation has been reported - to the extent that GM is now using that as a talking point.

Don't get me wrong, I understand there HAS to be some degradation based on battery chemistry, but it's just not being reported as a significant event on these cars. I wouldn't have expected thermal management to trump time and battery cycling to keep batteries going, but that sure appears to be the case.

If degradation is being hidden by a window, I'd expect that we'd be hearing about SOMEONE hitting that by now.

2013 SL with Premium package - build date 5/13. 12 bar car with 50,000 miles and counting... Trying to nurse 12 bars to 60,000 miles and beyond if possible!

GRA wrote:Just to be clear, the Volt's battery has suffered degradation but because GM decided to only use 65% of the total capacity when new, that degradation is hidden from the owner. In addition, they employed a very effective active TMS which slows down the rate of heat-related degradation, which combined with the relatively small SoC window allowed when new and the ability to open up that window as the battery ages, allows the Volt to appear to have no degradation from the user's perspective over a prolonged period of time.

Re: the bolded part, I've heard the Volt opening up more capacity as the battery degrades passed around both as speculation and fact by several different folks. I've also heard Volt folks claiming that the Volt does NOT do that.

I'm not clear who's right. Logically, it'd make sense for GM to do that. Whether or not they do it is a question...

If anyone has a definitive answer, preferably different independent sources providing evidence of one or the other, I'd like to know.

Not definitive but I've seen posts from GM engineers insist that the capacity window does not open up or change. This was on FB Q&A posts at the Gen 2 release as well as the GM Volt forums.

I've seen those claims too, and simply don't believe them (what, company reps fibbing to the public?), but as you say, until someone has a way to measure this we can't say for certain. OTOH, LG Chem would have had to invent a miracle battery for the Volt to have suffered zero detectable degradation with no change in usable SoC after 5.5 years, so weigh the probabilities.

Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'.Copper shot, not Silver bullets.

So, what this study shows is that if you Drive a Volt ~150 k miles, over 80% of those miles fueled by gas, with very little battery pack cycling, and continue to use gasoline to fuel your battery pack refrigeration system even after the battery charge is depleted, you will not have very much pack degradation over ~3.5 years, even in Phoenix.

You also will have burned more gas than you would have driving an efficient/hybrid ICEV, every kWh you used from the grid would have been totally wasted, and you would have suffered ~$36,000 in depreciation (before incentives).

So, what this study shows is that if you Drive a Volt ~150 k miles, over 80% of those miles fueled by gas, with very little battery pack cycling, and continue to use gasoline to fuel your battery pack refrigeration system even after the battery charge is depleted, you will not have very much pack degradation over ~3.5 years, even in Phoenix.

You also will have burned more gas than you would have driving an efficient/hybrid ICEV, every kWh you used from the grid would have been totally wasted, and you would have suffered ~$36,000 in depreciation (before incentives).

The INL test may be valid on degradation just based on the fact that 80% of the time the Volt battery was floating at the low SOC mark somewhat within operating parameters for most of the test period. I'm not sure the test methods beyond that even reflect the fleet they're trying to measure. For all other conclusions drawn? Not so much.

* All operating cost and cost per mile metrics are based on MSRP plus pricing. When was that ever valid for a Volt or a Leaf for that matter. Depreciation hurts, but I'm betting no one has taken a 36,000 hit on either car. To pick a nit, how many 38MPG highway cars are there and at what prices?

* The Volt fleet on Voltstats shows less than 1% of cars operating at 20% EV mode or less. Few drive this way and there is little financial benefit to do so. The median in that population is well over 75% of miles EV mode. At US average prices and EV efficiency of the Volt, gas is still about twice the price of electricity. More EV miles equal more savings. I don't see how every kWh from grid could be totally wasted when the cost is half of the gas equivalent.

Please let this Volt Driving Critical Thought Imbecile ask one more question, which was why I originally posted here. Do you think a 3 year old 40,000 mile LEAF at or approaching 11 bars would be good for a 40 mile commute for the next 3 years and 60,000 additional miles at potentially zero degree winter temperatures? One way with charging on both ends. I know a 3-5 yr old Volt can, but it would be interesting to try something different and save a 4,000 price premium on a used model Volt vs LEAF.

2013 SL with Premium package - build date 5/13. 12 bar car with 50,000 miles and counting... Trying to nurse 12 bars to 60,000 miles and beyond if possible!